The invention relates to a method for cleaning at least one filter of a vacuum cleaner, wherein the vacuum cleaner comprises a suction inlet and a dirt collection container, which is in flow connection with a suction unit via the at least one filter and a suction extraction line, and which can be subjected to negative pressure by the suction unit, and wherein for cleaning purposes the at least one filter can be acted upon by external air on the clean side via at least one external air valve, which moves from a closed valve position to an open valve position and back again into the closed valve position for cleaning the at least one filter.
The invention also relates to a vacuum cleaner for performing the method.
A vacuum cleaner of the kind mentioned at the outset comprises a suction inlet to which, for example, a suction hose is connectable in the usual manner. The suction inlet is in flow connection with the dirt collection container. It may, for example, be provided that the suction inlet opens directly into the dirt collection container or is in flow connection with it via an inlet line. The dirt collection container, in turn, can be subjected to negative pressure by the suction unit. For this purpose, the dirt collection container is in flow connection with the suction unit via at least one filter and a suction extraction line. By subjecting the dirt collection container to negative pressure, a suction flow can be created, under the action of which suction air laden with dirt can be sucked into the dirt collection container and then emitted to the environment again by the suction unit via the at least one filter and the suction extraction line. The at least one filter is arranged in the flow path between the dirt collection container and the suction unit, so that solid particles carried along with the suction flow are deposited on the side of the filter that is oriented towards the dirt collection container. The flow resistance of the filter increases as the deposit of solid particles increases and so it has to be cleaned after some time. For cleaning purposes, the clean side of the filter oriented away from the dirt collection container can be acted upon by external air. To do so, an external air valve, starting from a closed valve position, can be moved to an open valve position and then back into the closed valve position again. This has the consequence that external air can flow briefly into the suction extraction line and act upon the clean side of the filter. This results in a mechanical shaking of the filter, with at least part of the incoming external air flowing through the filter in counterflow direction, i.e., counter to the flow direction prevailing during normal suction operation. This boosts the cleaning effect of the filter.
Vacuum cleaners of the kind mentioned at the outset are known from WO 2008/014798. Cleaning of the filter can be carried out by acting on the at least one filter with external air as briefly as possible, without this causing any noticeable interruption in the suction operation.
The object of the present invention is to develop the method of the kind mentioned at the outset and a vacuum cleaner for performing the method such that the at least one filter can be cleaned particularly effectively.